In large-scale simulations such as molecular simulation and global warming simulation, one or more physical quantities are calculated and outputted at every timestep. Therefore, the amount of data of the sequentially outputted calculation results becomes huge.
Specifically, the amount of data outputted as above can be represented by the product of the mesh size in the physical space in which the calculation is performed, the number of timesteps, and the number of handled physical quantities. For example, in the model in which the mesh size in a three-dimensional space is 10,000×10,000×10,000, and the number of timesteps indicating the elapse of time is 100,000, and the number of physical quantities each represented by eight bytes is 100, the total amount of the output data is approximately 804 petabytes (804×1015 bytes). Therefore, the storage capacity of a hard disk or the like for storing the huge amount of data as above is necessary.
In addition, the output data as above are also used for displaying a simulation process by coupling the output data to a visualization device such as a display device. However, the processing time for displaying the huge amount of data also becomes huge.
As explained above, programs (such as simulation programs) which output a great amount of calculation results and perform analysis on the basis of the calculation results require a long processing time and great areas for storing calculation results.
Conventionally, in some cases, techniques of thinning out data are used for solving the above problems. For example, data are thinned out according to the variation rates of data sampled at predetermined time intervals (See, for example, Japanese Laid-open Patent Publication No. 2000-206105).
However, it is difficult to appropriately set the intervals at which the data obtained by performing simulation are thinned out. That is, in some cases where the thinning-out intervals are great, data in a time interval of interest or a spatial region of interest can be lost, i.e., necessary data can be lost. On the other hand, in the case where the thinning-out intervals are small, the amount of data cannot be greatly reduced.
In addition, in the case where the technique disclosed in Japanese Laid-open Patent Publication No. 2000-206105 is applied to a simulation of a phenomenon in a physical space with a large-scale model as mentioned before, and the spatial variation rates (the X-, Y-, and Z-axes in a three-dimensional space) and timewise variation rates (along the time axis) are obtained on a point-by-point basis in the physical space, the burden of calculation greatly increases since the handled data are multidimensional.